1. Field of the Invention
The present invention relates to an image processing apparatus, an image processing method, and an image processing program, and particularly relates to an image processing apparatus, an image processing method, and an image processing program for processing a background pattern representing additional information.
2. Description of the Related Art
Along with widespread use of digitized image information and development of image information processing technique in recent years, an image processing apparatus has achieved a remarkable development. Such a development results in the image processing apparatus (so-called a MultiFunction Peripheral (MFP), a Scan Print Copy (SPC), or an All In One (AIO)) which is equipped with functions of devices such as a copying machine, a printer, a facsimile, and an image scanner by itself. The image processing apparatus of this type has already been commercialized and even now the market of this apparatus is still expanding.
With further improvement of quality in performance and spread of the image processing apparatuses, a copy (such as electronic data, printed matters) which is substantially same as an original document can be prepared more easily than ever before. Therefore, problematic incidents from a viewpoint of information management have been frequently reported. Such incidents involve problems of diffusion and loss of information, with which information copying using the image processing apparatus is assumed to be involved. In response to demands from the market, several prior arts are developed. Below, those prior arts are described.
JP 06-022119 A discloses an image processing apparatus which is capable of identifying the document which requires security protection. This image processing apparatus can embed additional information which is used to identify the document, and also can read out and extract the embedded additional information. When the image processing apparatus duplicates the document in which the additional document is embedded, the image processing apparatus can count up the total number of the copy of the document according to the extracted additional information and duplicates the document with embedding second additional information in the duplicate based on the extracted additional information.
The image processing apparatus of JP 06-022119 A having above mentioned configuration is capable of identifying correspondence between a copied material and a specific material, a person who has copied the material, and the like so that this provides an effect of preventing a document from being copied illegally.
JP 2004-274092 A also discloses an image processing apparatus which is capable of identifying the document which requires maintaining its confidentiality. The image processing apparatus detects a background pattern embedded in background parts of the image of the document, and compares the detected background pattern with a prescribed and stored output prohibition pattern, and prohibits the output of the image of the document when the comparison results in matching.
The image processing apparatus disclosed in JP 2004-274092 A can also provide an effect of preventing a document from being illegally copied.
Both of the two image processing apparatuses mentioned above controls the duplication of a document by embedding the pattern representing predetermined additional information into the document. Typically, this pattern is quietly embedded in a predetermined area of a document in a format where a user can hardly understand the meaning of the information which the pattern represents. The area into which the pattern is embedded may be an arbitrary part of the document. However, an area having a monotonous color tone and a faint color is suitable for the pattern to be detected. In many cases, the suitable area is a peripheral edge part of a document.
However, an image processing apparatus typically has erase functions as optional functions of the copy function such as frame erase, fold line erase (center erase), and out-of-the-document-boundary erase. When copying a document with those erase functions, the background pattern embedded in the peripheral edge part or the central part of the document is also simultaneously erased.
As described above, the background pattern can be embedded and detected even in the area other than the peripheral edge part and the central part of the document. However, a problematic deterioration of the detection rate of the background pattern occurs when the background pattern embedded in the area such as the peripheral edge part is lost by the erase function since the peripheral edge part is advantageous for the embedded background pattern to be detected.
Other objects and further features of the present invention will be apparent from the following detailed description when read in conjunction with the accompanying drawings.